Process for the heat treatment of oils and fats, more particularly for the purpose of bleaching and hardening same



Patented May 28, 1935 PROCESS FOR THE HEAT TREATMENT OF OILS AND FATS, MORE PARTICULARLY FOR THE PURPOSE OF BLEACHING AND HARDENING SAME Wilhelm Gensecke, Gonzenheim, near Frankforton-the-Main, Germany, asslgnor to American Lnrgi Corporation, tion of New York New York, N. Y., a corpora- No Drawing. Application October 7, 1930, Serial No. 487,093. In Germany April 4, 1930 1 Claim.

The subject of the present invention is a process for the heat treatment of oils and fats, more particularly for the purpose of bleaching and hardening same. The process consists in 5 distilling off in vacuo the fatty acids freshly formed by the heat treatment during the heat treatment itself or directly after said treatment or alternating with the heat treatment, in a manner known per se by means of steam distillation or also with the employment of other inert gases. Insofar as this distillation occurs subsequent to the heat treatment, said distillation can be carried out at the temperature obtaining during the heat treatment, but the temperature can also be increased or decreased by a definite amount, before the vacuum treatment for the purpose of distilling oi! the fatty acids commences.

When bleaching crude, neutralized or deslimed or in any other way preliminary purifled vegetable or animal oils and fats with fullers earth, charcoal and the like at elevated temperatures (above 190 C.) free fatty acids are formed. The formation of fatty acids also occurs during the so-called hot bleaching, during which colouring matter is destroyed by elevated temperatures. When hardening oils by means of hydrogen in the presence of catalysts which process also takes place at elevated temperatures, the oils are similarly powerfully bleached. In this case also a portion of the oil or fat is decomposed with the formation of glycerine and free fatty acids.

This formation of fatty acids in the oils and fats is a very undesirable phenomenon since the neutralization of the oils and fats which have been treated at elevated temperatures, and which are therefore more or less polymerized, by means of alkalis or the like for the purpose of removing these fatty acids is rendered very diflicult.

The soaps into which the fatty acids are thus converted separate only with difiiculty from the neutral oil and large losses of neutral oil are caused thereby. Moreover, it is difllcult to wash the soap dissolved in colloidal condition out of the oils or fats which have been subjected to heat treatment, by means of water, since emulsions are frequently formed during the washing which are the cause of great losses of oil.

All these drawbacks are avoided in accordance with the present invention when the free fatty acids already present or produced in the course of the heat treatment are distilled off in vacuo by means of direct steam or of any other inert gases during the heat treatment or after cooling down the oil or fat to a definite temperature. In order to effect as rapid and as complete as possible a removal ofthe fatty acids, the process is advantageously carried out under a very low absolute pressure which can be reduced for example, to a pressure of 1 mm. hg. and less, to which end a steam jet apparatus can be inserted between the condenser for the fatty acids and the steam condenser.

The apparatus for carrying out the present process can be so arranged that the heat treatment and the distillation are carried out in one vessel. However, the process can also be carried out by spraying the oil which has been subjected to heat treatment in one vessel, into a second vessel which is preferably maintained under a very high vacuum under which circumstances the evaporation of the fatty acids occurs instantaneously. It is obviously also possible to employ other types of apparatus, without departing from the scope of the invention as defined by the appended claim.

Ezample 1a Maize oil which has been neutralized with alkali is heated to 280 C. in a vacuum apparatus, after separating off the fatty acid soaps, direct steam being passed through at the same time. During the heating, bleaching of the oil occurs and the free fatty acids thus formed are distilled off, the oil being then cooled down with the exclusion of air, and in this manner a light coloured maize oil which is practically free from fatty acids, is obtained.

Example 1b The maize oil is covered in a suitable apparatus, with an atmosphere of carbon dioxide, hydrogen or any other inert gas and is then heated with the exclusion of air. Inert gases may also be passed through the oil or fat during the heating. Prior to or after attaining the maximum temperature a vacuum is applied to the oil and the free fatty acids are distilled oh by means of steam, which is passed over or through the oil. Alternatively after attaining the maximum temperature the oil is cooled down to a suitable temperature whereupon a vacuum is applied to the apparatus and the fatty acids produced during the heat treatment are distilled off, the oil being subsequently cooled, with the exclusion of air.

Example 211 Crude maize oil is deslimed by means of dilute acids or acid earths and is then treated in a similar manner to that set forth in Example la or 1b.

Example 2b Fuller's earth charcoal or other bleaching agent is added to crude or preliminarily purified maize oil and the process is then carried out as set forth in Example 1a or 1b.

Example 3 Crude or deslimed maize oil is neutralized with alkali or the like and is then further treated as set forth in Example 2b.

Example 4 the free fatty acids produced are distilled off by means of steam which is passed through or over the oil, or else the oil is cooled down to a definite temperature at which no more decomposition can take place and is then subjected to distillation in a similar manner tothat hereinbefore set forth. The oil may also be sucked off from the hardening apparatus, after hardening, into a special vacuum apparatus wherein the free fatty acids are distilled off.

I claim:

The process of producing a neutral bleached edible oil or fat which comprises separating the albuminous and mucilagenous matter from a colored edible oil or fat, separating the free fatty acids therefrom by neutralization with alkali, heating the oil or fat to a temperature in the neighborhood of 280 C. for a sufllcient time to bleach the same, whereby free fatty acids are formed, and directly thereafter distilling off the free fatty acids in a vacuum with the aid of an inert gas.

WILHELM GENSECKE. 

